Interpol cited prison escapes in Iraq, Libya and Pakistan, and asked its members to examine if they were connected.

The police agency is also asking member countries to "swiftly process any information linked to these events".

In the most recent escape, 248 prisoners were sprung from a jail in north-west Pakistan.

Taliban militants used automatic weapons and bombs to break down the walls of the jail in Dera Ismail Khan on 30 July. At least 13 people were killed, including six police.

The authorities said 30 of those who fled were "hardened militants" jailed for involvement in suicide bombings and other serious attacks.

Hundreds of inmates escaped from two jails in Iraq - Abu Ghraib to the west of Baghdad and Taji to the north - on 22 July.

Bombs and mortar fire were used to break into the prisons. Al-Qaeda members were among those housed in the facilities.

'Terrorist attack'

There were several hours of fighting after the jails first came under attack and at least 20 members of the security forces were killed.

Five days later, some 1,200 inmates broke out of a jail in the restive Libyan city of Benghazi.

The US alert said the risk was particularly great in the Middle East and North Africa

"With suspected al-Qaeda involvement in several of the breakouts which led to the escape of hundreds of terrorists and other criminals, the Interpol alert requests the organisation's 190 member countries' assistance in order to determine whether any of these recent events are coordinated or linked," the French-based agency says.

It also calls for Interpol to be informed "if any escaped terrorist is located or intelligence developed which could help prevent another terrorist attack".

Calling for increased vigilance, Interpol says it is prioritising information and intelligence related to the breakouts.

Interpol's alert comes after the US state department issued a global travel alert because of fears of an unspecified al-Qaeda attack.

In its report, the New York Times says high-level intercepts were collected and analysed this week and that the CIA, state department and White House immediately recognised their significance.

The US state department said the alert expires on 31 August 2013 and it recommended US citizens travelling abroad be vigilant.

"Current information suggests that al-Qaeda and affiliated organisations continue to plan terrorist attacks both in the region and beyond, and that they may focus efforts to conduct attacks in the period between now and the end of August," the statement said.

The alert warned of "the potential for terrorists to attack public transportation systems and other tourist infrastructure".

Earlier, the US announced it was shutting nearly two dozen embassies and consulates in the Muslim world on Sunday.

Britain is closing its embassy in Yemen on Sunday and Monday as "a precautionary measure".

The boss of Twitter UK has said sorry to women who have experienced abuse on the social networking site.

Tony Wang said the threats were "simply not acceptable" and pledged to do more to tackle abusive behaviour.

The apology came as Twitter updated its rules and confirmed it would introduce an in-tweet "report abuse" button on all platforms, including desktops.

Police are investigating eight allegations of abuse including bomb and rape threats made against women.

Two people have been arrested in relation to rape threats against Labour MP Stella Creasy and feminist campaigner Caroline Criado-Perez, who received the threats after a campaign to have Jane Austen on the new £10 note.

The Guardian's Hadley Freeman, the Independent's Grace Dent and Time magazine's Catherine Mayer all said they had received identical bomb threats on Wednesday.

In a series of tweets, Twitter UK general manager Mr Wang said: "I personally apologize to the women who have experienced abuse on Twitter and for what they have gone through.

"The abuse they've received is simply not acceptable. It's not acceptable in the real world, and it's not acceptable on Twitter.

Tony Wang said Twitter would do more to tackle abusive behaviour

"There is more we can and will be doing to protect our users against abuse. That is our commitment."

Minister for Women and Equalities Jo Swinson told the BBC that unchecked Twitter abuse had been a problem for a long time and she was "delighted" the company was apologising and taking action.

Ms Mayer, Europe editor of Time magazine, said she had yet to receive a personal apology from Twitter, despite contacting the website.

"I'm deeply amused by the phrase I've received a personal apology from Twitter," she told the BBC News Channel.

"If he [Mr Wang] would like to make an apology to me, he can direct message me if he doesn't want to do it publicly."

She went on: "We're not being targeted because we're activists, we're being targeted because we're female."

Journalist and broadcaster Grace Dent received a bomb threat on Twitter

In an earlier message posted on the Twitter UK blog, the company's senior director for trust and safety, Del Harvey, and Mr Wang, said the company had clarified its anti-harassment policy in light of feedback from customers.

They said: "It comes down to this: people deserve to feel safe on Twitter."

The company has clarified its guidance on abuse and spam - reiterating that users "may not engage in targeted abuse or harassment".

The "report abuse" button already available on the iOS Twitter app and mobile site will also be rolled out to the main website and Android app from September, Twitter said.

They said in the blog that additional staff were being added to the teams that handle reports of abuse and the company was working with the UK Safer Internet Centre, which promotes the safe and responsible use of technology.

"We are committed to making Twitter a safe place for our users," they said, adding: "We're here, and we're listening to you."

“Start Quote

The current process [to report abuse] is lengthy, complicated and impossible to use if you're under sustained attack like I have been”

Caroline Criado-Perez

Ms Criado-Perez, 29, welcomed Twitter's response but said the process for reporting abuse should be further simplified to take the onus off the victim.

She said: "While I'm pleased they're listening, it's taken Twitter a week to come up with this.

"Twitter's 'report abuse' button on the iPhone application goes through to the old reporting form. What we're looking for is an overhaul of the system which sits behind the button.

"The current process is lengthy, complicated and impossible to use if you're under sustained attack like I have been.

"Right now, all the emphasis is on the victim, often under intense pressure, to report rather than for Twitter to track down the perpetrator and stop them."

Protesters say they are not convinced the investigation is sincere

Tens of thousands of people have rallied in Taiwan's capital, Taipei, to protest against the treatment of a young army conscript who died after being punished for misconduct.

Some 18 army officers, including a major-general, have already been charged in connection with the case.

The defence minister has also resigned.

Hung Chung-chiu, 24, was only three days away from completing his military service when he died of organ failure brought on by heatstroke.

Corporal Hung had been held in solitary confinement for bringing a mobile phone with built-in camera onto his military base - and was then subjected to arduous punishment exercises in the hot sun.

His death has generated outrage across Taiwan and damaged the standing of the army, which is already struggling to find enough volunteers as it tries to phase out conscription, says the BBC's Charles Scanlon.

President Ma Ying-Jeou has publicly apologised and promised justice for the family.